Optical coherence tomography (OCT) has revolutionized the ophthalmology practice since its introduction in 1991. It is a non-invasive imaging test which utilizes light waves to capture the cross sectional image of the retina and soft tissues lining behind the retina. It provides a microscopic image of the retina. It takes 2 or 3-dimensional picture of the retina by measuring the echo relay and back-reflected infrared light from internal light sensitive tissue structure. With the help of optical coherence tomography equipment, each of retina's layers can be seen individually which allows the ophthalmologist to measure and map the thickness of these layers. These mapping and measurements help ophthalmologists in the diagnosis and providing treatment guidelines for retinal disease such as glaucoma, diabetic eye disease, and age-related macular degeneration. Additionally, optical coherence tomography equipment are used to diagnose disorders of the optic nerve.